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<B><A HREF="STDIO.html">STDIO(3)</A></B>	       FreeBSD Library Functions Manual 	      <B><A HREF="STDIO.html">STDIO(3)</A></B>


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<H2>NAME</H2><PRE>
     <B>stdio</B> - standard input/output library functions


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<H2>SYNOPSIS</H2><PRE>
     <B>#include</B> <B>&lt;stdio.h&gt;</B>
     <B>FILE</B> <B>*stdin;</B>
     <B>FILE</B> <B>*stdout;</B>
     <B>FILE</B> <B>*stderr;</B>


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<H2>DESCRIPTION</H2><PRE>
     The standard I/O library provides a simple and efficient buffered stream
     I/O interface.  Input and output is mapped into logical data streams and
     the physical I/O characteristics are concealed. The functions and macros
     are listed below; more information is available from the individual man
     pages.

     A stream is associated with an external file (which may be a physical de-
     vice) by <I>opening</I> a file, which may involve creating a new file. Creating
     an existing file causes its former contents to be discarded.  If a file
     can support positioning requests (such as a disk file, as opposed to a
     terminal) then a <I>file</I> <I>position</I> <I>indicator</I> associated with the stream is
     positioned at the start of the file (byte zero), unless the file is
     opened with append mode. If append mode is used, the position indicator
     will be placed at the end-of-file.  The position indicator is maintained
     by subsequent reads, writes and positioning requests. All input occurs as
     if the characters were read by successive calls to the <B><A HREF="getc.html">fgetc(3)</A></B> function;
     all output takes place as if all characters were written by successive
     calls to the <B><A HREF="putc.html">fputc(3)</A></B> function.

     A file is disassociated from a stream by <I>closing</I> the file.  Output
     streams are flushed (any unwritten buffer contents are transferred to the
     host environment) before the stream is disassociated from the file.  The
     value of a pointer to a FILE object is indeterminate (garbage) after a
     file is closed.

     A file may be subsequently reopened, by the same or another program exe-
     cution, and its contents reclaimed or modified (if it can be repositioned
     at the start).  If the main function returns to its original caller, or
     the <B><A HREF="exit.html">exit(3)</A></B> function is called, all open files are closed (hence all out-
     put streams are flushed) before program termination.  Other methods of
     program termination may not close files properly and hence buffered out-
     put may be lost.  In particular, <B><A HREF="_exit.html">_exit(2)</A></B> does not flush stdio files.
     Neither does an exit due to a signal.  Buffers are flushed by <B><A HREF="abort.html">abort(3)</A></B> as
     required by POSIX, although previous implementations did not.

     This implementation makes no distinction between ``text'' and ``binary''
     streams.  In effect, all streams are binary.  No translation is performed
     and no extra padding appears on any stream.

     At program startup, three streams are predefined and need not be opened
     explicitly:
	   <B>o</B>   <I>standard</I> <I>input</I> (for reading conventional input),
	   <B>o</B>   <I>standard</I> <I>output</I> (for writing conventional output), and
	   <B>o</B>   <I>standard</I> <I>error</I> (for writing diagnostic output).
     These streams are abbreviated <I>stdin</I>, <I>stdout</I> and <I>stderr</I>. Initially, the
     standard error stream is unbuffered; the standard input and output
     streams are fully buffered if and only if the streams do not refer to an
     interactive or ``terminal'' device, as determined by the <B><A HREF="ttyname.html">isatty(3)</A></B> func-
     tion.  In fact, <I>all</I> freshly-opened streams that refer to terminal devices
     default to line buffering, and pending output to such streams is written
     automatically whenever such an input stream is read.  Note that this ap-
     plies only to ``true reads''; if the read request can be satisfied by ex-
     isting buffered data, no automatic flush will occur.  In these cases, or
     when a large amount of computation is done after printing part of a line
     on an output terminal, it is necessary to <B><A HREF="fflush.html">fflush(3)</A></B> the standard output
     before going off and computing so that the output will appear.  Alterna-
     tively, these defaults may be modified via the <B><A HREF="setbuf.html">setvbuf(3)</A></B> function.

     The <B>stdio</B> library is a part of the library <B>libc</B> and routines are automat-
     ically loaded as needed by the C compiler.  The SYNOPSIS sections of the
     following manual pages indicate which include files are to be used, what
     the compiler declaration for the function looks like and which external
     variables are of interest.

     The following are defined as macros; these names may not be re-used with-
     out first removing their current definitions with #undef: BUFSIZ, EOF,
     FILENAME_MAX, FOPEN_MAX, L_cuserid, L_ctermid, L_tmpnam, NULL, P_tmpdir,
     SEEK_CUR, SEEK_END, SEEK_SET, TMP_MAX, clearerr, feof, ferror, fileno,
     fropen, fwopen, getc, getchar, putc, putchar, stderr, stdin, stdout,
     vfscanf. Function versions of the macro functions <B>clearerr</B>(), <B>feof</B>(),
     <B>ferror</B>(), <B>fileno</B>(), <B>getc</B>(), <B>getchar</B>(), <B>putc</B>(), and <B>putchar</B>() exist and
     will be used if the macro definitions are explicitly removed.


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<H2>SEE ALSO</H2><PRE>
     <B><A HREF="close.html">close(2)</A></B>,	<B><A HREF="open.html">open(2)</A></B>,  <B><A HREF="read.html">read(2)</A></B>,  <B><A HREF="write.html">write(2)</A></B>


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<H2>BUGS</H2><PRE>
     The standard buffered functions do not interact well with certain other
     library and system functions, especially <B><A HREF="vfork.html">vfork(2)</A></B>.


</PRE>
<H2>STANDARDS</H2><PRE>
     The <B>stdio</B> library conforms to ISO 9899: 1990 (``ISO C'').


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<H2>LIST OF FUNCTIONS</H2><PRE>
     <B>Function</B>	    <B>Description</B>
     asprintf	    formatted output conversion
     clearerr	    check and reset stream status
     fclose	    close a stream
     fdopen	    stream open functions
     feof	    check and reset stream status
     ferror	    check and reset stream status
     fflush	    flush a stream
     fgetc	    get next character or word from input stream
     fgetln	    get a line from a stream
     fgetpos	    reposition a stream
     fgets	    get a line from a stream
     fileno	    check and reset stream status
     fopen	    stream open functions
     fprintf	    formatted output conversion
     fpurge	    flush a stream
     fputc	    output a character or word to a stream
     fputs	    output a line to a stream
     fread	    binary stream input/output
     freopen	    stream open functions
     fropen	    open a stream
     fscanf	    input format conversion
     fseek	    reposition a stream
     fsetpos	    reposition a stream
     ftell	    reposition a stream
     funopen	    open a stream
     fwopen	    open a stream
     fwrite	    binary stream input/output
     getc	    get next character or word from input stream
     getchar	    get next character or word from input stream
     gets	    get a line from a stream
     getw	    get next character or word from input stream
     mkdtemp	    create unique temporary file
     mkstemp	    create unique temporary file
     mktemp	    create unique temporary file
     perror	    system error messages
     printf	    formatted output conversion
     putc	    output a character or word to a stream
     putchar	    output a character or word to a stream
     puts	    output a line to a stream
     putw	    output a character or word to a stream
     remove	    remove directory entry
     rewind	    reposition a stream
     scanf	    input format conversion
     setbuf	    stream buffering operations
     setbuffer	    stream buffering operations
     setlinebuf     stream buffering operations
     setvbuf	    stream buffering operations
     snprintf	    formatted output conversion
     sprintf	    formatted output conversion
     sscanf	    input format conversion
     strerror	    system error messages
     sys_errlist    system error messages
     sys_nerr	    system error messages
     tempnam	    temporary file routines
     tmpfile	    temporary file routines
     tmpnam	    temporary file routines
     ungetc	    un-get character from input stream
     vasprintf	    formatted output conversion
     vfprintf	    formatted output conversion
     vfscanf	    input format conversion
     vprintf	    formatted output conversion
     vscanf	    input format conversion
     vsnprintf	    formatted output conversion
     vsprintf	    formatted output conversion
     vsscanf	    input format conversion

4th Berkeley Distribution	April 19, 1994				     3
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